1. Field of the Invention
The present invention relates to a method of and a system for generating teaching data for industrial robots, and more specifically to a method of and a system for generating teaching data from an off-line teaching apparatus.
2. Description of the Related Art
In the industrial field, robots have been widely employed in processes such as welding, etc. Teaching data used to activate these robots are generated by an off-line teaching apparatus. Then, the teaching data are stored in a robot controller and on-line teaching for making necessary corrections to the teaching data is effected while the robots are actually being operated. After such a process has been completed, the teaching data are put to practical use.
In the off-line teaching apparatus, a robot and an object (work) or the like are displayed on the screen of a graphic display as three-dimensional images. The operation of the robot is simulated on the three-dimensional images together with target points where a tool center point of the robot is to be positioned, based on previously-input work environment data including data about the shapes of the robot, jigs, a work, peripheral devices, etc. and previously-input operating performance data including data about the number of shafts of arms of the robot, the lengths of the arm shafts and acceleration and deceleration capability of each arm shaft. If the tool center point of the robot can reach each of the target points during that simulation, then data about coordinates of the target points, data about the position and attitude of the tool and data about the attitude of the robot are employed as teaching data.
Further, the correction of teaching errors developed due to errors in dimensions of the jigs and the work or the like, accumulated errors developed when the tool successively travels along teaching points, etc., is carried out off-line. Thereafter, on-line teaching is effected, thereby confirming, on an actual-object basis, the presence of an obstruction in the course of movement of the tool center point to each of the target points and a tool unattainable distance or the like. If necessary, the teaching data are corrected so as to produce finally practicable teaching data.
However, when the teaching data are created using the conventional systems described herein, there is often a situation in which the tool cannot reach each of the target points on simulated images. In this case, it is necessary for an operator who operates the off-line teaching apparatus to change the data about the coordinates of the target points and the data about the attitude of the tool either singly or in combination based on the operator's experiences and repeat trial and error in order to search or find out the position in the vicinity of each of the target points allowable on design, to which the tool can attain. Therefore, a great deal of time and labor are required to obtain proper teaching data on the simulated images. It is also difficult to avoid dependence on a personal skill.
Even if the teaching data obtained off-line in this way are used, various errors such as dimensional errors developed for each robot, errors in arrangement of each robot, errors in dimensions of jigs and a work, etc. cannot be completely corrected, thereby causing problems such as interference among the robot, the jigs and work on a production line, interference among other robots, etc. Thus, a process for correcting the teaching data by trial and error made on the actual-object basis, i.e., the on-line teaching, cannot be omitted.
In the on-line teaching, the teaching data which involve problems such as interference, etc., are used to actually operate the robots. It is therefore necessary to operate the robots with great caution. There is also often a situation in which the degree of freedom in the trial and error is limited at the time of the trial operations of each robot on-line. Accordingly, even this on-line teaching develops a problem in that a lot of time and labor and the skill of an operator are required.